Re: [PATCH v2 1/2] vdso: move offset_in_page() from linux/mm.h to vdso/page.h

[Andy Shevchenko]

On Thu, May 21, 2026 at 4:56 PM Lorenzo Stoakes <ljs@xxxxxxxxxx> wrote:
> On Thu, May 21, 2026 at 12:16:00PM +0100, Lorenzo Stoakes wrote:
> > On Thu, May 21, 2026 at 11:06:57AM +0200, Thorsten Blum wrote:

...

> Unless a series can be put forwards that sensibly justifies this, not some
> random change somewhere, I'd rather we not take it.

The problem is not only a compile time but more generic - the mess in
the Linux headers. People who want to use this match need to include
mm.h which is a bloated header with *tons* of unneeded dependencies
(for those pure users) and increases chaos in how the headers are
split.
If we don't care about it, then provide an "INCLUDE EVERYTHING" header
and let the driver just include that. But of course, we don't do that,
we do modular headers for a reason. Currently I see no reason to have
that simple helper to be mm.h as its use is much wider in the cases
where the whole hell of mm.h is not needed.

So, the best course of actions I see now is leave mm people alone and
simply duplicate what we need in the headers we want to see
(util_macros.h as a rough approximation, but maybe something better).


> Also vdso/page.h is a VDSO-specific header by MAINTAINERS, offset_in_page() is
> really an mm thing so that's another reason not to move it.
>
> (A justifying change would show actually build time/binary bloat/etc. numbers +
> involve actual substantive changes).



-- 
With Best Regards,
Andy Shevchenko